1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method. More particularly, the present invention relates to a digital image filtering apparatus and a digital image filtering method. Further, the present invention relates to a recording medium, such as a computer readable medium, having recorded thereon a processing program for permitting a computer to perform image processing routines.
The present application is based on Japanese Patent Application No. Hei. 11-280907, which is incorporated herein by reference.
2. Description of the Related Art
Conventionally, using filters to change the image quality of digital image data that are output is a well known process. In this explanation, unless otherwise specified, filtering represents a concept that includes spatial filtering, tone correction and gray level correction processes. Enhancement filtering, for example, which is a kind of spatial filtering, is a process for emphasizing the contrast between adjacent pixels to enhance detailing, such as at edges, around corners and along lines.
Generally, when an image processing application performs multiple kinds of filtering, these processes are performed in the order corresponding to that stipulated by an operator for the parameters established to perform the filtering, until finally, the results are output to a display. Thus, when for such an application an operator sets in a specific order parameters for spatial filtering and for gray level correction, for example, the processing is performed in that order. In addition, an operator may, while confirming the quality of an image output to a display, change the parameters for the performance of filtering by determining which parameters to use to obtain a desired image quality for the output of an image to a printer.
When the filtering of image data is performed, generally, as a result of the processing involved, color information and spatial information are reduced. For example, when the number of gray levels is reduced or increased to alter the brightness of an HSB (Hue, Saturation, and Brightness) model, two pixels that before the processing had different brightness levels may both have the same level after the processing has been completed. Also, a reduction in the total amount of color information, which is accomplished by employing a number of different processes for filtering, varies in consonance with the order in which the processes are performed. Therefore, the quality of the image data that is output fluctuates, depending in large part on the order in which filtering parameters are designated by a user.